Upland cotton (Gossypium sp.) is attacked by parasitic nematodes including the reniform nematode (Rotylenchulus reniformis Linford and Oliveria).  Options for management of reniform nematode are few.  No cultivars of upland cotton (G. hirsutum L.) have genetic resistance, and previous attempts to discover resistance within G. hirsutum have been limited.  Our objectives were to evaluate the USDA G. hirsutum collection for reaction to parasitism by R. reniformis, by measurement of eggs (reproduction) and vermiform number (nematode survival) as an indicator of nematode resistance.  In groups of fifty, 2088 accessions from the TX collection (primitive G. hirsutums that have never been U.S. cultivars) were evaluated in the greenhouse, using single plants in four replicates.  Accessions were planted in cone-tainers in sterile soil and inoculated with a mixture of R. reniformis isolates at a population of 1,000 juveniles and vermiform adults per 150 ml of soil.  After 60 d, soil populations of vermiform nematodes were determined, and eggs were extracted from the root system and counted.  Paymaster 'PM 1218' was included as a check in every experiment.  Some accessions did not germinate, and were not evaluated.  Out of 1973 accessions with at least one replication, none showed high levels of resistance.  Seven accessions (TX245, TX378, TX500, TX1419, TX1472, TX1565, and TX1765) had lower population development than PM 1218 after repeated evaluations.  Results indicated egg counts and vermiform counts were correlated, but not closely. Egg counts were higher and more variable than vermiform counts.  While some accessions showed levels of resistance that might be useful in cotton improvement, evaluation remains difficult and introgression of genes for reniform nematode resistance remains a long-term breeding objective.